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Cambridge International Examinations
Cambridge International Advanced Subsidiary and Advanced Level
* 3 6 2 0 6 6 6 2 8 1 *
9693/03
MARINE SCIENCE
Paper 3 A2 Structured Questions
October/November 2014
1 hour 30 minutes
Candidates answer on the question paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams or graphs.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
Write your answers in the spaces provided on the question paper.
The number of marks is given in brackets [ ] at the end of each question or part question.
Electronic calculators may be used.
You may lose marks if you do not show your working or if you do not use appropriate units.
At the end of the examination, fasten all your work securely together.
This document consists of 15 printed pages and 5 blank page.
DC (ST/CGW) 108736
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1
(a) Table 1.1 shows the mean percentage of three gases in the surface sea water and in the
atmosphere.
Table 1.1
percentage in
surface sea water
percentage in the
atmosphere
nitrogen
48
78
oxygen
36
21
carbon dioxide
15
0.04
gas
(i)
State a biological process that releases oxygen into the environment.
...................................................................................................................................... [1]
(ii)
State a biological process that releases carbon dioxide into the environment.
...................................................................................................................................... [1]
(iii)
Suggest one reason for the difference between the percentages of the gases in the
atmosphere and in surface sea water.
...........................................................................................................................................
...................................................................................................................................... [1]
(b) Fig. 1.1 shows the solubility of carbon dioxide in pure water at different temperatures.
4
3
solubility of carbon
dioxide / g kg-1
2
1
0
0
10
20
30
40
water temperature / °C
Fig. 1.1
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60
3
(i)
With reference to the information in Fig. 1.1, describe the effect of temperature on the
solubility of carbon dioxide.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(ii)
The solubility of carbon dioxide in sea water is less than in pure water.
On Fig. 1.1, sketch a curve to show the effect of temperature on the solubility of carbon
dioxide in sea water.
[1]
(c) (i)
Explain what is meant by the term thermocline.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(ii)
Describe the effect of a thermocline on the availability of carbon dioxide at different
depths of the ocean.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(d) The surface temperature in the North Atlantic Ocean ranges from 12 °C to 16 °C.
The surface temperature in the Mid-Atlantic Ocean ranges from 22 °C to 26 °C.
Explain how the difference in the availability of carbon dioxide in these two regions of the
Atlantic Ocean might affect the population of primary producers.
...................................................................................................................................................
...................................................................................................................................................
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.............................................................................................................................................. [2]
[Total: 12]
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(a) Explain why marine fish tend to lose water to the sea.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [3]
(b) Fig. 2.1 shows the change in concentration of body fluids of three types of organism, A, B and
C, exposed to a range of different salinities of water.
A
B
concentration
of body fluids
C
salinity of water
Fig. 2.1
State, with reasons, which of these organisms, A, B or C, is likely to be a mussel and which is
likely to be a marine bony fish.
mussel ....................
reason .......................................................................................................................................
...................................................................................................................................................
marine bony fish .....................
reason .......................................................................................................................................
.............................................................................................................................................. [4]
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(c) Table 2.1 shows the concentration of some of the solutes present in sea water and in the
body fluids of fish living at different depths.
Table 2. 1
concentration of solute within fluid / mmol dm−3
solute
sea water
surface
water shark
surface water
bony fish
mid water
bony fish
benthic
bony fish
urea
0
363
4
1
2
trimethylamine oxide
0
66
14
12
51
chloride ions
550
235
176
267
242
sodium ions
470
230
198
282
225
With reference to Table 2.1 state which fish:
(i)
is likely to lose least water
...................................................................................................................................... [1]
(ii)
is likely to lose most water.
...................................................................................................................................... [1]
(iii)
Suggest an explanation for your answers to (i) and (ii).
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [3]
(iv)
Suggest a role in osmoregulation for urea and trimethylamine oxide.
...........................................................................................................................................
...................................................................................................................................... [1]
[Total: 13]
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3
(a) Table 3.1 shows some of the stages of the life cycle of the penaeid shrimp.
Table 3.1
stage
duration of stage
size at end of stage / mm
habitat
egg
14 hours
0.02
underwater offshore
nauplius larva
48 hours
0.50
surface water
offshore
protozoea larva
160 hours
2.59
mysis larva
72 hours
4.3
post larva
24 hours
4.6
migrate during
development
inshore
estuaries, mangroves
and coastal wetlands
juvenile
2–3 months
95–100
adult
6–12 months
180–250
(i)
State the location of the breeding grounds of the adult shrimps.
Give a reason for your answer.
...........................................................................................................................................
...................................................................................................................................... [1]
(ii)
Explain why large numbers of eggs and sperm are produced by these shrimps.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(iii)
State two advantages to the larval stages of penaeid shrimps of living in surface water.
1. .......................................................................................................................................
...........................................................................................................................................
2. .......................................................................................................................................
...................................................................................................................................... [2]
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(iv)
Young juvenile shrimps are scavengers, feeding on sediment. As they age, juvenile
shrimps also become predators of planktonic crustacea, small fish and worms.
Table 3.1 shows that the habitat of juvenile shrimps is estuaries, mangroves and coastal
wetlands.
Explain why this habitat is advantageous to juvenile shrimps.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(b) Commercial aquaculture of shrimps along the coast of South America has increased greatly.
Large ponds are dug out along coastlines, destroying any mangroves or wetlands in the way.
The ponds are stocked with juvenile shrimps and a food supply. After about four months, the
ponds are drained and the adult shrimps collected, cleaned and frozen for export.
(i)
Suggest two long-term economic disadvantages to local people of mangrove destruction.
1. .......................................................................................................................................
...........................................................................................................................................
2. .......................................................................................................................................
...................................................................................................................................... [2]
(ii)
Suggest two ways in which destruction of mangroves for shrimp aquaculture might affect
the local ecosystem.
1. .......................................................................................................................................
...........................................................................................................................................
2. .......................................................................................................................................
...................................................................................................................................... [2]
[Total: 11]
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4
(a) The management of sustainable fishing involves monitoring and enforcement of regulations.
(i)
Explain what is meant by fisheries monitoring.
...........................................................................................................................................
...................................................................................................................................... [1]
(ii)
Describe two aspects of commercial fishing which are monitored.
1. .......................................................................................................................................
...........................................................................................................................................
2. .......................................................................................................................................
...................................................................................................................................... [2]
(iii)
Describe how two different types of surveillance system might be used.
1. .......................................................................................................................................
...........................................................................................................................................
2. .......................................................................................................................................
...................................................................................................................................... [2]
(iv)
Suggest one way in which a fishing vessel could be recognised by surveillance systems.
...........................................................................................................................................
...................................................................................................................................... [1]
(b) (i)
Describe how three enforcement methods can help to keep commercial fishing
sustainable.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [3]
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(ii)
Describe three difficulties in enforcing fishing regulations.
...........................................................................................................................................
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...................................................................................................................................... [3]
[Total: 12]
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5
(a) State what is meant by the term aquaculture.
...................................................................................................................................................
.............................................................................................................................................. [1]
(b) Salmon is one of the world’s most economically important fish in aquaculture. A small
percentage of these fish are genetically engineered (GM salmon).
Outline how salmon have been genetically engineered to increase growth rate.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [3]
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(c) Salmon have been modified by artificially increasing the chromosome number so that they
are sterile. This has been done with both normal salmon (non-GM salmon) and on salmon
genetically engineered to increase growth rate (GM salmon).
An investigation was carried out into the sizes of salmon in four groups:
•
group A
GM salmon with normal chromosomes
•
group B
GM salmon with extra chromosomes
•
group C
non-GM salmon with normal chromosomes
•
group D
non-GM salmon with extra chromosomes
The fish produced were weighed. The maximum and minimum size in each group was
recorded and the mean mass of each group calculated.
Fig. 5.1 shows the mean mass and size range for each of the groups, A, B, C and D.
GM salmon
non-GM salmon
600
500
size range
400
mean
mass / g
300
200
100
0
A
B
C
group
Fig. 5.1
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13
(i)
State why type C salmon were included in the investigation.
...........................................................................................................................................
...................................................................................................................................... [1]
(ii)
State the difference in the maximum mass of GM salmon with extra chromosomes and
the maximum mass of non-GM salmon with extra chromosomes.
...................................................................................................................................... [1]
(iii)
The mean mass of GM salmon with extra chromosomes is 2.5 times the mean mass of
non-GM salmon with extra chromosomes.
Calculate, for salmon with normal chromosomes, how much the mean mass of GM
salmon has increased compared to the mean mass of non-GM salmon.
........................................................... [2]
(iv)
With reference to Fig. 5.1, describe the effect of extra chromosomes on the growth of
salmon.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(d) Artificially adding extra chromosomes to fish used for aquaculture has been practised for at
least ten years.
Suggest two reasons why this type of fish is used for aquaculture.
1. ..............................................................................................................................................
...................................................................................................................................................
2. ..............................................................................................................................................
.............................................................................................................................................. [2]
[Total: 12]
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(a) Fig. 6.1 shows the world sources of mercury pollution.
key
burning fossil fuel
gold production
metal production
cement production
waste incineration
others
Fig. 6.1
(i)
Use Fig. 6.1 to identify the source that is responsible for approximately a quarter of the
world’s mercury pollution.
...................................................................................................................................... [1]
(ii)
Suggest two ways in which mercury might enter the ocean.
1. .......................................................................................................................................
...........................................................................................................................................
2. .......................................................................................................................................
...................................................................................................................................... [2]
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(b) Mercury can enter marine food chains.
Sea water contains 0.1–2.0 nanograms (ng) of mercury per kilogram of water.
Table 6.1 shows the mercury concentration in different trophic levels in the marine environment.
Table 6.1
trophic level
(i)
mercury concentration / ng kg−1
phytoplankton
10 000–100 000
zooplankton
20 000–100 000
molluscs and crustaceans
50 000–220 000
fish
100 000–420 000
predatory fish
330 000–1 080 000
Suggest one route by which mercury pollutants can enter marine food chains.
...........................................................................................................................................
...................................................................................................................................... [1]
(ii)
With reference to Table 6.1, explain why the concentration of mercury increases from
one trophic level to the next.
...........................................................................................................................................
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...........................................................................................................................................
...........................................................................................................................................
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...................................................................................................................................... [4]
(iii)
Describe how the increase in mercury in higher trophic levels might affect human food
sources.
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [1]
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(a) An ocean fishery is about to close because the main target fish population has collapsed.
The main fishing fleet is based in a deep water harbour next to the fish market. Support
businesses for fishing, such as rope and net sales and boat repairs, are in the same area.
There are two proposals to try and find alternative employment after the fishery closes.
Proposal 1
•
Local developers will expand the harbour and build a marina for leisure boats.
•
Fishing boats will be converted to use for sight-seeing or tourist hire around the coast.
•
The support businesses will remain to supply leisure boats.
•
In the market area, gift shops and food outlets will be developed for visitors.
Proposal 2
•
Outside developers will build a semi-extensive aquaculture fishery, partly based on land
and partly on a sea cage platform outside the harbour area.
•
Some of the fishing boats will be kept to transport farmed fish to the harbour and to catch
wild stock to supply the aquaculture.
•
In the long term, a fish processing business will be developed in the harbour area.
Two of the local stakeholders are the fishing boat owners and the support business owners.
(i)
Suggest one argument each of these stakeholders might make in favour of proposal 1.
fishing boat owners ...........................................................................................................
...........................................................................................................................................
support business owners ..................................................................................................
...................................................................................................................................... [2]
(ii)
Suggest one argument each of these stakeholders might make in favour of proposal 2.
fishing boat owners ...........................................................................................................
...........................................................................................................................................
support business owners ..................................................................................................
...................................................................................................................................... [2]
(b) At a public meeting with stakeholders, the view of the local people was that proposal 1 was
more risky than proposal 2.
Suggest two reasons why proposal 1 is less likely to succeed than proposal 2.
1. ..............................................................................................................................................
...................................................................................................................................................
2. ..............................................................................................................................................
.............................................................................................................................................. [2]
[Total: 6]
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Copyright Acknowledgements:
Question 1b
Question 2c
Question 3a
Question 5c
Question 6a
www.engineering toolbox.com/gases-solubility-water-d_1148.html
Griffiths; Biological Bulletin Vol 160, No. 2; Marine Biological Laboratory
http://www.aquaculture.ugent.be/Education/coursematerial/online courses/shrimp-cd/bio/table1b.htm
http://www.biofortified.org/2010/10/salmon
www.nrdc.org/health/effect/mercury/sources.asp
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2014
9693/03/O/N/14